Re: Auxiliary Compressor Air Flow to Level on '01
Reply #25 –
Mike and Mike, The check valves are the Achilles heels here. If they are not working then lots of different things can happen.
I think Mike H meant the check valve in line 75. If that fails then for air to go from the HWH tank to either of the service tanks the check valves at those tanks would have to fail and the pressure in the servce tank would have to be above the protection valve minimum level.
The check valve in line 57 is most likely there to isolate that part of the system (HWH compressor, HWH tank, bladder manifold and bladder) from the maybe higher pressure air from the engine driven compressor and perhaps from the braking systems. The DOT has lots of rules about what you should and should not do with the air bakes system.
If the check valve in line 57 was not there or failed then air from the front and rear tanks or from an external source (OEM Aux Air fitting) would pressurize the HWH tank and could be used to create the vacuum to deflate the bladder and reinflate it. Is that such a bad thing? Maybe not. With engine air you could operate the bladder if the HWH compressor failed. The compressor is protected by a check valve. I don't see any reason for it to be there. (Maybe some DOT rule) If you wanted to limit pressure to the HWH tank and the bladder manifold you could add a pressure regulator set to maybe 95 psi after the check valve in line 75.
If you added a second aux air line connection (with a valve) between the engine compressor and the dryer in line 1 then you could add air that would be dried into the wet tank and then into the service tanks. I think there is a spare connection on the D1 governor where this could connect as well and not have to cut any lines. If your service tank pressure drops below the pressure protection valve minimum level then as I understand it the protection valve acts like a check valve in both directions and you cannot introduce air to them through the OEM aux air connection.
So getting rid of the check valve in line 57, adding a pressure regulator in line 75 and a valve and air connection fitting in line 1 seem like good things to do. The smaller compressor in this series of coaches is just not big enough to fill the HWH tank, the wet and front and rear service tanks.
Document changes.
If you make any changes to the air system or your electrical systems do yourself and the next owner a favor by documenting the changes and additions. Diagrams, sketches, descriptions and pictures all help us remember what we did and why.
FYI, later build numbers.
At build 5920 they started using a bigger compressor. It still has a check valve in line 57 but there is a line with a check valve to the wet tank and from there to both the front and rear tanks, a lot more volume to keep up to pressure. The HWH bladder seal tank also provides air to the awning, the toilet, a second slide bladder manifold and maybe a tag manifold.
For build number 6024 and 6060 and beyond the air step is gone as is the air operated awning and all four tanks had easily accessible drain valves, something that is also worth adding.
Topic: Auxiliary Compressor Air Flow to Level on '01